In the building industry, especially that concerned with the building of houses, formwork bricks are increasingly being used, especially for cellars. They generally consist of concrete. Formwork bricks can, however, also be used for the complete walls of a house. In general, only the first layer of brick is set in mortar and the remainder of the wall is put up in dry condition in the form of modules or building bricks so that even people who are not experts in building can erect such structures.
Formwork bricks are therefore manufactured relatively accurately to size and mostly provided with groove and tongue for fitting together.
After the formwork bricks have been laid together one above the other to the desired height, their cavities are filled with concrete. This extremely simple process results in a very stable wall which has, however, very little in heat insulation properties.
For this reason, that is, to improve heat insulation, formwork bricks have been developed with insulating inserts.
Such a formwork brick is described in the DE-OS 19 16 400. It consists of light concrete and with an admixture of foamed plastic particles, and has an external wall, an internal wall, two face walls and a central connecting wall. The cavities formed by the brick connections are shielded at least on one side with plates of thermally insulated material. Noses or lug or ribs project inwards serving to hold these plates. The face walls and the connecting wall are provided at their top and bottom edges with semi-circle-shaped recesses to permit the overflow of the concrete to be filled in from one brick into the next in horizontal direction.
Another such formwork brick is also revealed in DE 34 32 925. It consists of an eternal wall, an internal wall and two face walls. In this formwork brick, too, an insulating insert is used to improve thermal insulation and soundproofing. This insert extends without interruption over the inside of the external wall, the insides of the two face walls and along the recesses which are located in the end faces and are used for filling with concrete. Although the above described formwork bricks possesses good heat insulating characteristics, they are still capable of being improved. The same considerations apply to the soundproofing characteristics of formwork bricks.